THE NEW HONG KONG FLU

By Christine Gorman

Few people outside the medical community paid much attention last May when a three-year-old Hong Kong boy died of a mysterious flu that usually infects only birds. Even this fall, when seven more people came down with the same viral strain--and one of them died--doctors found comfort in the fact that the virus did not seem to be spread from person to person. But then last week two young cousins of one of the victims fell ill with what appeared to be the same disease, prompting medical authorities in the U.S. and China to warn that this might be the beginning of a larger outbreak. It did not take long for the press to start making comparisons with the great flu epidemic that killed 20 million people in 1918-19.

From two deaths to millions may seem like a big leap. But this strain of influenza, called H5N1, though highly virulent in birds, has never before been known to attack humans. Since no human can count on having a natural immunity to what is essentially a bird virus, we could prove especially vulnerable to infection. First discovered in South African terns in 1961, H5N1 has already raced through poultry farms in southern China, killing caged fowl by the thousands.

As far as health officials can tell, every patient with H5N1 flu was infected directly by a chicken or some other feathered creature. As long as the virus is being passed bird to person, rather than person to person, it is not likely to spread beyond a few isolated cases.

That is what makes the latest two cases--one of which has been confirmed to be the same disease--so important. If the virus has reconfigured itself into a form that can be passed from person to person, without an animal intermediary, and if that altered virus is highly contagious, Hong Kong's tiny outbreak could grow into a global pandemic. It is a long shot, but influenza viruses have performed such feats in the past, usually by trading key genes with other influenza viruses. These mix-and-match sessions seem to happen most often in pigs but can also occur in other mammals, including people.

Rather than wait to see what the H5N1 virus does next, U.S. scientists are racing to develop an effective vaccine, working in conjunction with doctors in Hong Kong and the pharmaceutical industry. It is not going to be easy. Influenza vaccines are usually grown in a chicken-egg medium, and H5N1 virus kills chicken eggs. "We've never been faced with this situation," says Dr. Anthony Fauci, head of the National Institute for Allergy and Infectious Diseases. Even if scientists succeed in genetically engineering a form of the virus that does not kill the eggs, says Fauci, it will still take another six months to develop, test and produce a viable vaccine. By that time, we may already know whether H5N1 has triggered one of those global epidemics that make the history books, or has snuffed itself out and become just another intriguing footnote.

--By Christine Gorman. With reporting by Sandra Burton/Hong Kong

With reporting by Sandra Burton/Hong Kong